Nancy is making cookies for a bake sale. she needs a total of 4 pounds of chocolate chips. she has a 28-ounce bag of chocolate chips, but the store now only has 10-ounce bags. how many bags of chocolate chips does nancy need to buy?

How many ounces are in a pound? 16! SO 16 times 4 = 64.  So Nancy needs 64 ounces in all.  So 28 plus 10 = 38 that's still not enough, so lets add some more 38 plus 10 = 48 still not enough, add some more 48 plus 10 plus 10 = 68.  So lets add up how many bags we need.  So in all with her 28 that she already has, we need 4 bags.